Unchecked render_view() in RenderViewObserverHelper class

In qtwebengine/src/core/renderer/user_resource_controller.cpp all usages of render_view() are unchecked and can be confused with globalScriptsIndex, which is always 0.
In the class description of RenderViewObserver it says:

  // A subclass can use this to delete itself. If it does not, the subclass must
  // always null-check each call to render_view() becase the RenderView can
  // go away at any time.

-> All return values of render_view() need to be checked against 0. I attached a patch for the Qt 5.9.1 source.